Filling the Memory of a Casio fx-4000P

Filling the Memory of a Casio fx-4000P

How many programs does it take to fill the 550 step memory?   Here are six programs that pretty much does the job.   I purposely aimed for descriptive prompts and messages. 

Spaces are added for readability.  

Here's are the six programs:

Prg 1:  Approximating the cumulative distribution function of the Normal Curve - to 3 decimal places

Mode +:  COMP,  Number of Steps: 82

"Z≥0" : ?→Z : Fix 3 : 1 - ((1+.196854 Z +.115194 Z² + .000344 Z^3 + .019527 Z^4)^ -4) ÷ 2 : Rnd : Norm : "AREA=" ◢ Ans → A

Source:  Abramowitz and Stegun, Handbook of Mathematical Functions. 1972.

Examples:

Z = 1.6

Results:  AREA = 0.945

Z = 1

Results:  AREA = 0.841

For best results, enter a positive Z.  

Prg 2:  Binomial Distribution PDF with Mean and Variance 

Mode +: COMP, Number of Steps: 86

"P(WIN)" : ?→P : "TRIALS" : ?→T : "WINS" : ?→N : "PDF=" ◢ T nCr N × P x^y N × (1-p) x^y (T-N) ◢ "MU=" ◢ T P  ◢ "VAR=" ◢ Ans (1 - P)

Note:  The combination function, nCr, is shown on the screen as a lone solid C.  I have the nCr for clarification.  

P(WIN):  probability of a successful event

TRIALS:  number of events

WINS:  number of successful events

PDF:  probability of we get the number of successful events

MU:  expected value, mean - depending on P(WIN) and TRIALS

VAR:  variance - depending on P(WIN) and TRIALS

Example:

P(WIN) = 0.7,  TRIALS = 25, WINS = 10

Results:  PDF = 1.324897424 x 10^-3, MU= 17.5, VAR= 5.25   

Prg 3:  Angles of a triangle given 3 side lengths in Degrees - Solve a SSS (side-side-side) Triangle

Mode +: COMP,  Number of Steps: 86

Deg : "A" : ?→A : "B" : ?→B : "C" : ?→C : "<A=" ◢ cos^-1 ((A² + B² - C²) ÷ (-2 B C))  → D ◢ "<B=" ◢ sin^-1(B sin D ÷ A) → E ◢ "<C=" ◢ 180-D-E→F 

Angle <A  (stored in D) is opposite of side with length A

Angle <B (stored in E) is opposite of side with length B

Angle <C (stored in F) is opposite of side with length C

Degrees mode is set in the program.  

Example:

Triangle with lengths A = 24, B = 60, C = 44

Results:  <A = 20.04997572,  <B = 58.99241697, <C = 100.9576073

Prg 4:   Free Fall with Air Resistance (from Ke!san)  

Assume coefficient is standard at k = 0.24 kg/m

(angle is not needed, hyperbolic trig does not depend on angle unit)

Site:  https://keisan.casio.com/exec/system/1231475371

(last retrieved:  February 27, 2023)

Mode +:  COMP,  Number of Steps:  88

.24 → K : 9.80665 → G : "MASS" : ?→M : "DIST" : ?→D : √(M ÷ G ÷ K) → X : "TIME=" ◢ 

X cosh^-1 (e(D K ÷ M)) → T ◢ "VEL=" ◢ X G tanh(T ÷ X) → V

SI units are assumed.

Example:

MASS = 68 kg, DIST (free fall distance) = 1874 m

Results:  TIME = 39.27745305 s, VEL (velocity at free fall) = 52.71191359 m/s

Prg 5:  Sums of 1 to n for k, k^2, k^3, and K^4

Mode +:  COMP, Number of Steps:  83

"1 TO..." : ?→N : "K =" ◢ N (N+1) ÷ 2 → S ◢ "K²=" ◢ S (2 N + 1) ÷ 3 → T ◢ 

"K◢3=" ◢ S² → U ◢ "K◢4=" ◢ T (3 N² + 3 N - 1) ÷ 5 → V 

The power character, x^y can not be used in a string or an error occurs.  The stop character, ◢, can be used.  

K:   Σ (K from K = 1 to K = N)

K²:  Σ (K^2 from K = 1 to K = N)

K◢3:  Σ (K^3 from K = 1 to K = N)

K◢4:  Σ (K^4 from K = 1 to K = N)

Example:  

N = 9

Results:

K:  45

K²:  285

K◢3:  2025

K◢4:  15333

Prg 6:  Simple Ohm's Law Wheel/Volts, Current, Resistance:  "PIE" chart

Mode +:  COMP, Number of Steps: 121

Lbl 0 : "ENT 0 TO SLV" ◢ "I" ◢ ?→I : "V" ◢ ?→ V : "R" ◢ ?→R : I=0 ⇒ Goto 1 : V=0 ⇒ Goto 2:  R=0 ⇒ Goto 3: Goto 0:  Lbl 1:  "I="  ◢ V ÷ R → I ◢ Goto 4: Lbl 2: "V=" ◢ I R → V ◢ Goto 4: Lbl 3: "R=" ◢ V ÷ I → R ◢ Lbl 4: "END"

I:  current (amps, A)

V: voltage (volts, V)

R:  resistance (ohms, Ω)

The inputs will be in this order.  Enter a zero for the variable you want to solve for.  

Examples:

Solve for I:  I = 0, V = 12, R = 3

Result:  I = 4

Solve for V:  I = 20, V = 0, R = 30

Result:  V = 600

Solve for R:  I = 17, V = 120, R = 0

Result:  R ≈ 7.05

Total Number of Programs: 6

Total Steps Used: 121 (I only have 4 left)

Eddie

All original content copyright, © 2011-2023.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 

Integrating Absolute Value Functions

Integrating Absolute Value Functions

Calculating ∫ abs(f(x)) dx

The function abs(f(x)) can be broken into two parts, depending on the sign of f(x):

abs(f(x)) = 

{   f(x)  when f(x) > 0

{  -f(x)  when f(x) < 0

General procedure:

1.  Find the roots of f(x).  

2.  Split the integral at the roots.

3.  For areas where f(x)>0, calculate the sub-area ∫ f(x) dx.

4.  For areas where f(x)<0, calculate the sub-area ∫ -f(x) dx.

5.  Total all the sub-areas.

Let's illustrate this with examples.  Screen shots are made with the HP Prime emulator.  The absolute value function |f(x)| is graphed in blue, while f(x) is graphed in red (for illustrative purposes).  

Example 1:  ∫ |4x- 2| dx from x = 0 to x = 5

∫ |4x- 2| dx from x = 0 to x =5

The root of (4x - 2) is x = 1/2.     

When x < 1/2, (4x - 2) < 0.   

When x > 1/2, (4x - 2) > 0.

Break down the integral into:

∫ (|4x- 2| dx from x = 0 to x =5)

= ∫ ( -(4x- 2) dx from x = 0 to x =1/2) + ∫ (4x- 2 dx from x = 1/2 to x =5)

=  1/2 + 81/2

=  82/2

=  41

We can type in the entire integral into a calculator or app.  Depending on the function and the advanced engine of the calculator, the accuracy may be affected.   Calculators and apps with advanced engines include the HP Prime, Wolfram Alpha, and Desmos.   (Your mileage may vary)

Example 2:  ∫ |x^3 - 28x + 48| dx from x = 0 to x = 3

∫ |x^3 - 28x + 48| dx from x = 0 to x = 3

The roots of x^3 - 28x + 48 are at x = -6, x = 2, and x = 4.   Since the root x = 2 is the only root in the interval [0, 3], this is the one root we are working with.  

With root x = 2, 

When x < 2, x^3 - 28x + 48 > 0

When x > 2, x^3 - 28x + 48 < 0

Then:

∫ ( |x^3 - 28x + 48| dx from x = 0 to x = 3 ) 

= ∫ ( (x^3 - 28x + 48) dx from x = 0 to x = 2 ) 

+ ∫ ( -(x^3 - 28x + 48) dx from x = 2 to x = 3 ) 

= 44 + 5.75

= 49.75

Example 3:  ∫ |e^(2x) - 2| dx from x = 0 to x = 2

The root of e^(2x) - 2 is x = ln 2 ÷ 2 ≈ 0.34657

Let A = ln 2 ÷ 2, and with root x = A,

When x < A, e^(2x) - 2 < 0

When x > A, e^(2x) - 2 > 0

∫ ( |e^(2x) - 2| dx from x = 0 to x = 2 )

=  ∫ ( -(e^(2x) - 2) dx from x = 0 to x = A ) + ∫( (e^(2x) - 2) dx from x = A to x = 2)

≈ 0.193147 + 22.99222

≈ 23.18537

Where is where this method returns approximates and using different calculators and apps may not produce the same results.  

HP Prime:  23.1853693777

Desmos:  23.1853693777

Wolfram Alpha:  23.1853693776920

TI-30X Pro MathPrint:  23.18537052

Hope this technique helps, 

Eddie

All original content copyright, © 2011-2023.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 

TI-84 Plus CE Python and TI-83 Premium CE Python Edition: Blinking Binary Strings

TI-84 Plus CE Python and TI-83 Premium CE Python Edition:  Blinking Binary Strings

Introduction

The script BINBLANK.py draws a circle's whose color changes based on a list of binary numbers:  green for 1, yellow for 0.  

The code listed is made for the TI-84 Plus CE Python and TI-83 Premium CE Python Edition.  

Program Script: BINBLANK.py

# ews 2023-06-24

# blink of lights: binary bits

from random import *

from ti_system import *

from ti_draw import *

# set subroutines

def black():

  from ti_draw import *

  set_color(0,0,0)

def white():

  from ti_draw import *

  set_color(255,255,255)

def yellow():

  from ti_draw import *

  set_color(255,255,0)

def lime():

  from ti_draw import *

  set_color(0,255,0)

def dcircle():

  from ti_draw import *

  fill_circle(150,100,50)

# using pixels, not coordinates

# initialization

blist=[]

print("Binary String Lighting")

print("Choose 1 or 2:")

print("1. generate random string")

print("2. enter a bit list")

# key press

k=0

# flag

f=0

while f==0:

  k=wait_key()

  if k==143:

    # 1 key

    n=int(input("Number of bits? "))

    blist=[randint(0,1) for i in range(n)]

    f=1

  if k==144:

    # 2 key

    blist=eval(input("List of bits: "))

    # data check

    m=len(blist)

    for i in range(m):

      if blist[i]!=0 and blist[i]!=1:

        1/0

        # force an error and terminate

    f=1

# draw the light

clear()

black()

fill_rect(0,0,319,209)

white()

dcircle()

# loop

for i in range(len(blist)):

  sleep(.1)

  if blist[i]==0:yellow()

  if blist[i]==1:lime()

  dcircle()

  black()

  sleep(.55)

  # reset

  white()

  dcircle()

# end indicator

black()

dcircle()

white()

# no line breaks in draw_text 

draw_text(50,50,"THE END: PRESS CLEAR")

show_draw()

Download the file:  https://drive.google.com/file/d/16nxEe51KEhTIX3p1E0uAzHUxCvElQTWE/view?usp=sharing

Notes:  

Three modules are used:  random, ti_system, and ti_draw.  The modules ti_system and ti_draw are Texas Instruments-specific modules.

The ti_system module allows for a get key type of function called wait_key().   wait_key() stops execution and waits for the user to press a key.   The value of the key is returned.   There are separate key combinations with [ 2nd ] or [ alpha ].  

The [ 1 ] key returns a value of 143.

The [ 2 ] key returns a value of 144. 

Here are some other key values:

[ 3 ]   145

[ 4 ]   146

[ 5 ]   147

[ 6 ]   148

[ 7 ]   149

[ 8 ]   150

[ 9 ]   151

[ 0 ]   142

[ enter ]   5

[ ← ]   2

[ → ]   1

[  ↑  ]  3

[  ↓  ]  4

[ clear ]  9

The script also checks self-entered lists to see that each entry is a 0 or 1.   If not, the program "calculates" 1 ÷ 0 to cause a program-stopping error.  

Eddie

All original content copyright, © 2011-2023.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 

Casio fx-9750GIII: Coin Flips and Probability of Winning

Casio fx-9750GIII:  Coin Flips and Probability of Winning

Introduction

The program COINPROB answers two questions in probability:

Take a game, with the chance of winning p.    There are only wins (success) and losses (failures).  Each game is independent and has the same chance of win.

1.  What is the chance of having an amount of wins in a set amount of games?   The binomial distribution is used to answer this question.

2. How many losses must be endured before a win occurs?  For this question, we turn to the geometric distribution.

Three results are listed are:

PDF:  the probability

MEAN:  expected value

VAR:  variance

The probability of success is also listed.

Casio fx-9750GIII Program:  COINPROB

Program Code:

(most spaces are added for readability)

"EWS 2023-06-25"

.5 → P

Locate 1, 4, "P(WIN) = P"

Locate 1, 5, "P(LOSS) = 1-P"

Locate 1, 6, "GAMES = TRIALS" ◢

Lbl 0

ClrText

Menu "PROB WIN VS LOSS", "SETTINGS", S, "# WINS IN GAMES", 1,

"# LOSS BEF. WIN", 2, "EXIT", E

Lbl S

Menu "SETTINGS", "P(WIN) = 0.5", F, "SET P(WIN)", U

Lbl F

.5 → F

"P(WIN) = .5"

"P(LOSS) = .5" ◢

Goto 0

Lbl U

"P(WIN)"? → P

"P(LOSS) = "

1 - P ◢

Goto 0

Lbl 1

"# GAMES"? → N

"# WINS"? → S

N nCr S × P^S × (1 - P)^(N - S) → P

N × P → M

M × (1 - P) → V

Goto R

Lbl 2

"# LOSSES"? → F

(1 - P)^(F - 1) × P → D

P⁻¹ → M

M × (1 - P) ÷ P → V

Goto R

Lbl R

ClrText

Locate 1, 3, "PDF= "

Locate 7, 3, D

Locate 1, 4, "MEAN="

Locate 7, 4, M

Locate 1, 5, "VAR="

Locate 7, 5, V

Locate 1, 6, "P(WIN)="

Locate 9, 6, P ◢

Goto 0

Lbl E

"THANK YOU"

Note:  The bold C is the combination function (nCr).  

Examples

1.  A fair coin is flipped.  You win if the coin flipped is heads.   What is the probability that you win 7 out of 10 times?

P = 0.5

# GAMES?  10

# WINS?  7

Problem Type:  # WINS IN GAMES

Results:

PDF=  0.1171875

MEAN= 5

VAR= 2.5

P(WIN)= 0.5

2.  What is the probability that you flip 7 tails before flipping a head?  Assume a fair coin.

P = 0.5

Problem Type:  # LOSS BEF. WIN

# LOSSES? 7

Results:

PDF=  0.0078125

MEAN= 2

VAR= 2

P(WIN)= 0.5

3.  On any given day in Luau Town, the chance of rain is 35% each day.   On a given week, how many days are expected to be sunny?

WIN:  sunny days (because that is what we want)

P(WIN) = 1 - 35% = 65% = 0.65

We want the mean (expected value).

Problem Type:  # WINS IN GAMES

Change P(WIN) to 0.65 in settings.  

# GAMES?  7  (7 days)

# WINS? (since we are interested in the mean, we can enter any number 0 to 7)

Results:

PDF= (N/A)

MEAN= 4.55

VAR= 1.5925

P(WIN)= 0.65

A week is expected to have about 4.55 sunny days.  Expected value does not have to be an integer.

4.  Assuming the chance of rain is 35% in Luau Town, what is the chance that there are 3 rainy days before a sunny day?

WIN:  sunny days, P(WIN) = 0.65

# LOSSES?  3

Results:  

PDF= 0.079625

MEAN= 1.538461538

VAR= 0.8284023669

P(WIN)= 0.65

Eddie

All original content copyright, © 2011-2023.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 

Python: Basic Functions with Quaternions

 Python:   Basic Functions with Quaternions   

Calculating with Quaternions

Quaternions are four-dimensional hypercomplex numbers that is written as the form:

r = a * i + b * j + c * k + d

We can also write quaternions as a four dimensional vector [a, b, c, d].

In computer graphics, quaternions are used to draw, display, move, and rotate 3D objects.  The constant term, d, is a mass-point, while the other three terms describe the location of vector point.

Some Mathematical Properties of Quaternions

The conjugate of a quaternion is similar to what a conjugate of a regular complex number would look like:

r* =  - a * i - b * j - c * k + d  

Similarly, the norm of a quaternion works in a familiar fashion:

| r | = abs(r) = √(a^2 + b^2 + c^2 + d^2)

We can multiply a quaternion by any scalar, s, as follows:

s * r = s*  a * i + s * b * j + a* r3 * k + a* r4  

To find the unit vector (unit quaternion), multiply the quaternion by the scalar 1/|r|.

Adding quaternions is communicative and associative.  However, multiplying quaternions is associative, but not communicative.  In short, when it comes to multiplying quaternions, order matters.  

For the complex coefficients:

i^2 = j^2 = k^2 = -1

i * j =  k,    j * i = -k 

j * k = i,   k * j = -i

k * i = j,  i * k = -j

List of Functions Included in QUAT.py

Quaternions are entered as vectors:

r = a * i + b * j + c * k + d -> [a, b, c, d]

qplus(r, q):   addition, r + q

qminus(r, q):  subtraction, r - q

qtimes(r,q):  multiplication,  r * q

qdivide(r,q):   division (multiply by the reciprocal):  r / q  = r * q^-1

qnorm(r):  norm or magnitude

qconj(r):  conjugate

qscale(r, a):   multiply quaternion r by a scalar a

qinv(r):  inverse or reciprocal of a quaternion,  1/r = r* / |r|

qsquare(r):  r^2

qhelp():  brings up the list of functions in QUAT plus.  

To use these functions on other Python scripts:

from QUAT import *

Important QUAT should also import the math module.  

Python:  Quaternions

This should work on all Python platforms since only the math module is used.  This was programmed on a TI-84 Plus CE Python calculator.

Python Code:  QUAT.py

# arithmetic with quaternions

# ews 2023-06-20

from math import *

# help

def qhelp():

  s="Quaternions - qhelp()"

  # add \n for new lines

  s+="\nEnter r=ai+bj+ck+d as [a,b,c,d]."

  s+="\nqplus(r,q) +  qminus(r,q) -"

  s+="\nqtimes(r,q) *  qdivide(r,q) /"

  s+="\nqnorm(r) magnitude \nqconj(r) conjugate \nqscalar(r,a) scalar mult. by a"

  s+="\nqinv(r) r**-1 qsquare(r) r**2"

  # need print to look nice

  return print(s)

# add

def qplus(r,q):

  return [r[i]+q[i] for i in range(4)]

# subtract

def qminus(r,q):

  q=[-i for i in q]

  return qplus(r,q)

# conjugate

def qconj(r):

  return [-r[i] for i in range(3)]+[r[3]]

# norm

def qnorm(r):

  s=sum([i**2 for i in r])

  return sqrt(s)

# inverse/reciprocal

def qinv(r):

  r=qconj(r)

  s=qnorm(r)

  s*=s

  return [i/s for i in r]

# scalar multiplication

def qscalar(r,a):

  return [a*i for i in r]

# multiplication

def qtimes(r,q):

  s=[0,0,0,0]

  s[0]=r[0]*q[3]+r[1]*q[2]-r[2]*q[1]+r[3]*q[0]

  s[1]=-r[0]*q[2]+r[1]*q[3]+r[2]*q[0]+r[3]*q[1]

  s[2]=r[0]*q[1]-r[1]*q[0]+r[2]*q[3]+r[3]*q[2]

  s[3]=r[3]*q[3]-r[0]*q[0]-r[1]*q[1]-r[2]*q[2]

  return s

# division

def qdivide(r,q):

  q=qinv(q)

  return qtimes(r,q)

# qsquare

def qsquare(r):

  return qtimes(r,r)

qhelp()

Download the script here:  https://drive.google.com/file/d/1iNDxw82Gm1nOVJ7jDHdnIIxA4tcaV0p3/view?usp=sharing

Source

Ron Goldman,

Understanding quaternions,

Graphical Models,

Volume 73, Issue 2,

2011,

Pages 21-49,

ISSN 1524-0703,

https://doi.org/10.1016/j.gmod.2010.10.004.

(https://www.sciencedirect.com/science/article/pii/S1524070310000172)

Science Direct requires a paid subscription or access through a university.

Alternate source:  https://www.researchgate.net/publication/220632454_Understanding_quaternions

All original content copyright, © 2011-2023.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 

TI-84 Plus CE Python: Drawing Random Paths

TI-84 Plus CE Python: Drawing Random Paths

Introduction

The Python script PATHS draws a path from the left side to one of the other three sides of the screen:  bottom, right, or up.  

The path is laid on a 70 x 70 grid, consisting on 10 x 10 blocks.  Due to the how the screen is set up, the grid does not look like squares.   A random number between 1 and 3 is picked and the path moves in one of three ways:

1:  The path moves up

2:  The path moves right

3:  The path moves down

Three modules are used:

>  random module

>  ti_draw module (exclusive to TI):  drawing commands

>  time module (exclusive to TI):  used for the sleep command

TI-84 Plus CE Python Script:  paths.py

This code should work on the TI-83 Premium CE and the TI-Nspire CX II.  

# draw a random path

# EWS 2023-06-19

from ti_draw import *

from random import *

from time import *

clear()

set_window(0,70,0,70)

# initialization

set_color(0,128,0)

x=0

y=40

# draw using upper left corner

fill_rect(x,y,10,10)

# main loop

while x<60 and y>10 and y<60:

  r=randint(1,3)

  if r==1:

    y+=10

    set_color(0,0,224)

  if r==2:

    x+=10

    set_color(0,128,0)

  if r==3:

    y-=10

    set_color(255,165,0)

  fill_rect(x,y,10,10)

  sleep(.25)

# set end indicator

set_color(0,0,0)

fill_rect(0,40,10,10)

fill_rect(x,y,10,10)

# text - allow for text height

# have to play around

set_color(255,255,255)

draw_text(2,42,"BGN")

draw_text(x+2,y+2,"END")

show_draw()

Notes:

>  The show_draw() command on the end let's us see all the steps.   A sleep command (time module) at the end of the loop to slow down between each execution of the loop.

>  The fill_rect both take coordinates to be the upper-left hand corner of box.  

>  The draw_text works similarly to fill_rect except we have to account for the size of the font.   

>  The set_window command allows us to set the coordinates for the window.  If there is no set_window command, the screen would operate by pixels instead. The TI-84 Plus CE screen is 319 x 209 pixels.  

Three example paths are shown below:  

Eddie 

All original content copyright, © 2011-2023.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 

HP 15C Collector's Edition: Some Thoughts and Hidden Modes

HP 15C Collector's Edition:   Some Thoughts and Hidden Modes

On May 2, 2023, Moravia announced the return on the HP 15C programming scientific calculator.  An initial limited run  calculators were available that were delivered in July. Thankfully, another set of calculators will be available for order and delivery starting the end of September 2023.

Hopefully this will be true in future production runs, but in the initial run, the HP 15C came in a box, a Thank You card,  with a leather case and a printed manual.    I love the larger font and the clarity of the text of the Owner's Handbook.   The handbook is an extension of the original HP 15C Manual along with an introduction from Wlodek Mier-Jedrzejowicz and Gene Wright.  

You can download both the Manual and new edition of the Advanced Functions Handbook from the HP Calculator Literature website:

Manual:  https://literature.hpcalc.org/items/2258

Advanced Functions Handbook:  https://literature.hpcalc.org/items/2259

The compliment to Manual, the Advanced Functions Handbook goes into detail on several of the HP 15C's advanced features:  

Solving Equations:   The best ways for using the SOLVE command, and how the SOLVE feature finds roots of equations.  This section also includes a section of finding the derivative (approximate slope) of a function and a financial time-value-of-money program.

Integration:  The accuracy of the integral function and handling more difficult integral problems.  In general, the accuracy and the time of integration is tied to the fixed decimal settings.

Complex Numbers:  The internal workings of the complex mode (Flag 8), including solving equations and integrations.

Matrices:  LU Decomposition, constructing identity matrices, and least-squares calculations.

Programming:  No More Pause Bug

The PSE bug has been fixed!  We can use the pause command to heart's content and the display won't flash off.  

Back of the Calculator

The back of the HP 15C has a plate that has the following information:  statistics registers, some conversions, a table of error, test, and matrix codes, how the ISG (increment skip if greater than) and DSE (decrement skip if equal) commands work, and the stack effects on several two-result commands.

The Keyboard

The battery compartment, which contains the two CR2032 batteries needed to power the HP 15C is held by a small screw.  Thankfully, no special screwdriver is required, a small household or computer screwdriver should do the trick.

The keyboard, for me, is responsive.  The keys give a nice, quiet click when they are pressed.  I'm comfortable holding the calculator and letting my thumbs type on the keyboard efficiently.

Hidden Modes

Already, the HP 15C Collector's Edition has additional memory over the previous editions:

*  A maximum of 99 memory registers, 78 uncommitted registers at default setting

*  A maximum of 672 steps

We have some Easter Eggs on the HP 15C Collector's Edition.   There are two hidden modes on the HP 15C:

HP 15.2 Mode:  This mode ups the maximum of memory registers to 195, with 174 uncommitted registers at default setting.    Pressing [ g ] ( MEM ) at the beginning will show "19174 00-0", as there really isn't enough room to display the total amount of uncommitted registers.  I have my calculator in 15.2 mode and so far, this calculator works as well as the default HP 15 mode.  Switching back to 15 mode will preserve as much memory as allowed, excessive memory will be lost.  

HP 16 Mode:  This modes accesses a possible-beta version of the HP 16C calculator.   The HP 16C calculator was a popular computer programmer's calculator which emphasizes on bit manipulation, base conversions, and Boolean logic.   I worked a little bit on this mode, and there was a few problems when working in decimal integer mode.     More information on the HP 16C calculator here:  https://www.hpmuseum.org/hp16.htm

How do we switch the hidden modes on the Collector's Edition?

1.  With the calculator off: hold the [ g ], [ ENTER ], and [ ON ] keys.   This gets the calculator into test mode.

2.  Press [ 4 ].  Option 4 will not appear on the screen.

3.  Set your mode:

   * [ e^x ] for the original HP 15C Collector's Edition mode

   * [ 1/x ] for the expanded 15.2 mode  (not manufacturer supported)

   * [ 7 ] for the HP 16C mode (not manufacturer supported)

Caution:  The 15.2 and 16 modes are not manufactured supported.  Enter at your own risk.  For me, I have used the 15.2 mode and the calculator works fine.  The original mode still has plenty of memory.  

Discussion on the hidden modes starts about page 17 of this thread:

https://www.hpmuseum.org/forum/thread-19886-page-17.html

Final Thoughts

Welcome back, HP 15C!  Knock on wood the HP 15C once again becomes mainstream like it's long time financial cousin the HP 12C.

Need help with RPN (Reverse Polish Notation)?  Check out the RPN Programming tutorial series (which was done for the previous HP 15C Limited Edition) which starts here:  http://edspi31415.blogspot.com/2011/11/hp-15c-programming-tutorial-part-1.html

(Just keep in mind the pause bug that was present in the Limited Edition has been fixed in the Collector's Edition.)

Eddie 

All original content copyright, © 2011-2023.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author.